Epidemiology of Salmonella enterica serotype typhi infections in Korea for recent 9 years: trends of antimicrobial resistance

Abstract

The aim of this study is to characterize the epidemiological features of typhoid fever, categorized as class 1 notifiable disease in Korea and to analyze the recent change of antimicrobial resistance of Salmonella enterica serotype Typhi isolated nationwide. We retrospectively analyzed the 1,692 culture-proven cases from 1992 to 2000, using the data of the Korean National Institute of Health. The overall incidence of culture-proven typhoid fever was 0.41 per 100,000 population. It occurred all over the country, but the southeastern part of Korean peninsula had the higher incidence rate than other areas. There were several outbreaks suspected, of which two outbreaks were confirmed. The resistance rate against chloramphenicol showed mild increase, but the ampicillin, trimethoprim/sulfamethoxazole, kanamycin, or nalidixic acid resistance remained at the similar levels for the past 9 yr. There were 21 (1.3%) multidrug-resistant (MDR) strains isolated since 1992, and the number of those has increased. Two strains resistant to ciprofloxacin were first identified in Korea.

Fig. 1

Monthly occurrence of culture-proven typhoid fever for recent 9 yr in Korea. The incidence reached its peak from April to June every year, and there were two outbreaks confirmed in 1996.

Fig. 2

Vi phage types of isolates by time (A) and the region of occurrence (B). There is considerable diversity in proportion of each phage type by year or region of occurrence. It is noted that the proportion of phage type A has a tendency to increase steadily as times passed.